replace C-style include files with their C++ equivalents

src/MC/pair_dsmc.cpp

@@ -15,10 +15,11 @@
    Contributing authors: Paul Crozier (SNL)
 ------------------------------------------------------------------------- */
 
-#include <math.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cmath>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <climits>
 #include "pair_dsmc.h"
 #include "atom.h"
 #include "comm.h"
@@ -28,7 +29,6 @@
 #include "domain.h"
 #include "update.h"
 #include "random_mars.h"
-#include <limits.h>
 
 using namespace LAMMPS_NS;